Class 2

Soldering how-to

If you are interested in seeing some more advanced stuff, check out Sparkfuns series of tutorials on soldering. It's mostly surface-mount examples, but the basic principals on how solder moves and what the common issues are the same with through-holes parts.

Eagle Schematics and Board Design

We went through some commands in class. Here are what we talked about, and a basic description:

ADD: Load a new part into you Schematic (not available in Board design)

Assemble Interactive Marquee Letter

TIP120 Pinout

We will use a TIP120 transistor so that you can drive super bright LEDs if you'd like. Those require more current than your Arduino/ATtiny85 pin can output, so we use a transistor to turn on and off those higher currents.

Class 4

Feb 22

Assemble our Marquee Sign

Great jog everyone, everyone's PCBs work!!! Find the sign assembled and hanging on the wall.

Larger AVR Microcontrollers

The ATtiny84 (on digikey) is just like the ATtiny85, except it has more pins. The ATtiny84/85 are both fairly easy to solder down compared with other microcontrollers and modules.

The ATMega328p (on digikey) is the most popular microcontroller around, it's what powers the Uno, Pro Mini, Adafruit Metro, and many others. It is difficult to solder down, but it's such a great chip that maybe you'll want to give it a try. Also, it does not support an "internal" clock, so you need to add a crystal or resonator to you circuit (we have 8mhz resonators in the cage).

The ATMega32u4 (on digikey) is very similar to the 328p, except it has hardware USB support, so it can act as a USB device.

Surface-Mount Packages

When selecting surface mount (SMD) components, it is important to pay close attention to the package (the shape) that the part comes in. If your components are not the same shape as in your Eagle file, then they will not be able to fit onto your PCB.

In the image above, you can see that the ATtiny85's package is what's called an SO-8 or SOIC-8. The ATtiny84's package is similar but with more pins, it's called an SO-14 or SOIC-14

Also, the 3.3v 0.5A regulator that we have in the cage is an SOT-223 package like in the picture above.

Passive components are things like resistors, capacitors, and LEDs. We have many reels of these parts in the cage, all of which are 0603 SMD part sizes. So when ADD'ing parts to you schematic, make sure your passive components are 0603.

"Wireless" NETs in Schematic Files

NETS in Eagle Schematic files are the green lines that connect PINS together. Each NET has a unique name, like for example "VCC" and "GND". If two NETS are given the same name, then they are connected to each other, allowing you to "connect" PINS in your schematic without having to draw those lines.

Starting with an unconnected PIN, draw a small NET coming out of it connected to nothing else

Right-click the NET, and select "Label" from the menu that pops up

The name of that net will now show up and you can place it

Right-click the NET again, and select "Name" from the menu

Name it the same name as another NET in your schematic, and now they are connected

Order any prototyping parts for your midterm project, and get you circuit/code/interaction working so you can start designing your PCB and ording parts.

Class 5

Feb 26 (rescheduled for 9am)

Adding Ground-Plane in Eagle

A "ground-plane" is when, instead of ROUTE'ing your GND connections, you can draw a POLYGON that fills in the entire PCB with your GND signal. Ground-planes help shielding noise, cooling your circuit, and often times making production a little simpler.